WATER PRESSURE CHANGE IN MOVABLE BED REGARDING SIMILARITY LAW FOR GEOMATERIAL BY DEAN NUMBER ON WAVE FLUME EXPERIMENT

Abstract

 Flow movement of soil sediment induced by ocean wave is caused by a complex interaction between traction force and seepage force. In this study, we conducted a series of wave flume experiment with movable-bed focusing on the influence of the traction and seepage forces for soil movement phenomena. In the experiments applied the Froude's similarity law and Dean Number were employed for the seletion of seabed materials. The experimental results were validated with the exact solution which was derived by means of u-p formulation of seabed as a two-phase material consisting of solida and fluid. Toyoura Sand which was selected as the prototype, showed that the change in stress inside soil sediment was not able to be reproduced, where the phase difference of pore water pressure transmission with depth was not recognized. On the other hand, Silica Sand No. 8 which was selected with the account of Dean Number equivalency, showed that the behavior of pore water transmission inside soil sediment properly. In the observation the phase angle change in excess pore water pressure with depth was recognized; the observed phase angle transmission was similar to the predicted one by means of exact solution. As a result, we found that the change in ground stress induced by wave loading in 1g field experiment can be appropriately reproduced using the soil material which with the account of the equivalency of Dean Number.